Of the many items automakers put on their Christmas lists is the wish for every government to unanimously agree on every law imposed on them. No industry enjoys such treatment, but as builders of the world’s most regulated consumer product, you can’t blame automakers for trying. Their lobbyists are calling for the U.S. and the European Union to merge their safety requirements into one overarching standard.

Those lobbyists claim that automakers are charged the equivalent of a “25-percent or more” tariff when exporting cars across the Atlantic due to the higher costs of meeting standards in one or both regions. To prove that unifying crash tests and thousands of similar laws could work, they’ve commissioned a study between the University of Michigan Transportation Research Institute and its Swedish counterpart at Chalmers University.

“The U.S. and Europe have the most advanced auto-safety regulations in the world, and in many cases, the differences between the standards are very modest,” Rob Strassburger, a representative of lobbyist group Auto Alliance, said in a statement.

The World Forum for Harmonization of Vehicle Regulations, run by the United Nations, has been trying since 1958 to get countries on the same page. And outside of the U.S. and E.U., automakers have been quite content selling cars with substandard or deleted safety equipment in the name of higher profits. Unified regulations would go some way to doing away with such practices—and a proposed free-trade agreement could pave the way for such action.

Both the U.S. and E.U. sweat the small stuff, which won’t make a single set of regulations any easier. European crash tests require automakers to meet standards for pedestrian impacts, whiplash, and infant protection—even infant dummies and car-seat installations are evaluated for each car—and while the U.S. government necessitates these tests, their performance in them isn’t scored. (With the odd exception of the Tesla Model S, the U.S. refuses to crash-test expensive, low-volume cars, while Maseratis and Range Rovers get rated in Europe.)

The National Highway Traffic Safety Administration, citing a lack of research, bans advanced safety technologies like BMW’s Dynamic Light Spot, which detects and illuminates pedestrians and animals in low-light conditions, yet NHTSA also mandates a more stringent roof-crush test than in Europe. Independent groups like the Insurance Institute for Highway Safety, which has all but required automakers to install stronger front crash structures in the U.S., complicate things even more. For example, while the Feds can’t agree on how to test active safety features, the IIHS is mirroring European tests for evaluating auto-braking systems.

To a regulator’s eye, automakers are making plenty of money on cars that meet both U.S. and E.U. safety laws, so arguing for a common standard on economic grounds looks weak. On this matter and many more, count on the two regions agreeing to disagree.